Specifications

CAVR-4
80
Checking module consistency
AVR® IAR C/C++ Compiler
Reference Guide
Examples
For an example of using the runtime model attribute __rt_version for checking
module consistency on used calling convention, see Hints for using the new calling
convention, page 100.
The following assembler source code provides a function, part2, that counts the
number of times it has been called by increasing the register
R4. The routine assumes
that the application does not use
R4 for anything else, that is, the register has been locked
for usage. To ensure this, a runtime module attribute,
__reg_r4, has been defined with
a value
counter. This definition will ensure that this specific module can only be linked
with either other modules containing the same definition, or with modules that do not
set this attribute. Note that the compiler sets this attribute to
free, unless the register is
locked.
RTMODEL "RTMODEL "__reg_r4", "counter"
MODULE myCounter
PUBLIC myCounter
RSEG CODE:CODE:NOROOT(1)
myCounter: INC R4
RET
ENDMOD
END
If this module is used in an application that contains modules where the register R4 has
not been locked, an error is issued by the linker:
Error[e117]: Incompatible runtime models. Module myCounter
specifies that '__reg_r4' must be 'counter', but module part1
has the value 'free'
USER-DEFINED RUNTIME MODEL ATTRIBUTES
In cases where the predefined runtime model attributes are not sufficient, you can define
your own attributes by using the
RTMODEL assembler directive. For each property, select
a key and a set of values that describe the states of the property that are incompatible.
Note that key names that start with two underscores are reserved by IAR Systems.
For example, if you have a UART that can run in two modes, you can specify a runtime
model attribute, for example uart. For each mode, specify a value, for example mode1
and mode2. You should declare this in each module that assumes that the UART is in a
particular mode. This is how it could look like in one of the modules:
#pragma rtmodel="UART", "mode1"